A mixer typically has insertion loss and multiplies an input signal with a reference signal to generate an output signal having a predetermined amount of gain. The frequency components of the output signal are determined by the frequency components of the input signal and the frequency components of the reference signal.
When mixing very low level signals, there is a need to amplify the mixed signals before further processing is performed. Hence, the need for an amplifier stage. In wide band applications, the mixer stage and the amplifier stage must be designed to respond to the entire frequency band of operation. These are difficult design requirements.
It is difficult to fabricate a wide band mixer on a die for use as an integrated circuit (IC). It is even more difficult to fabricate an ultra wide band active mixer on a die having gain across a frequency band that spans from direct current (DC) up to a frequency in excess of 20 GHz. The present invention addresses such a mixer.